New simpler API available for accessing fields, properties and language information

The EntityInterface got the following methods, that can now be used on entities inheriting from this interface:

• language() - returns the default language of a language-specific entity.
• translations() - returns the languages the entity is translated to.
• get() - to retrieve property or field values in a specific language, no need to fiddle in the field arrays on entities anymore!
• set() - to update property or field values in a specific language, no need to fiddle in the field arrays on entities anymore!

The basic usage for the new accessors is pretty straightforward:

<?php
  // Change a field value.
  $body = $comment->get('comment_body');
  $body[0]['value'] = 'This is actually a perverted tango';
  $comment->set('comment_body', $body);

  // A plain property is handled the same way.
  $created = $comment->get('created');
  if ($created > REQUEST_TIME) {
    watchdog('warning', 'Ahead of their times');
  }
?>

Also language-aware access has been greatly simplified:

  // Retrieve a translation:
  $german_body = $comment->get('comment_body', 'de');

  // Set a translation:
  $german_body[0]['value'] = 'updated';
  $comment->set('comment_body', $german_body, 'de');

The following example just updates all translations:

  // Retrieve the comment body in the original language. No need to specify one
  // here as the default is the original language.
  $original = $comment->get('comment_body');
  // Loop over the comment translations and provide a comment body value for
  // each one.
  foreach ($comment->translations() as $langcode => $language) {
    // We want to provide a value only for translations, hence we skip the
    // original language.
    if ($langcode != $comment->language()->langcode) {
      $body = array();
      $t_args = array('@language' => $language->name, '%original' => $original[0]['value']);
      $body[0]['value'] = t('This is the @language translation of %original', $t_args, array('langcode' => $langcode));
      // Here we need to specify the property language the passed value must be
      // assigned.
      $comment->set('comment_body', $body, $langcode);
    }
  }